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Photo: Thalictrum venulosum

Thalictrum venulosum Trel.

Boundary Meadow-Rue

Habitat: Prairies, thickets, open woods and shores.

Range: Labrador and Quebec south to Maine and New York, west to British Columbia and Yukon Territory, south to New Mexico.

Photo: Thalictrum venulosum

Aids to Identification: Meadow-rues are recognized by their alternate, divided leaves, panicles of yellowish greenish or pinkish flowers with numerous stamens, and leaflets with lobed margins. Boundary meadow-rue has small flowers in a panicle and leaflets with 4 or more lobes. The leaflets have distinct veins. The achenes are curved. It may resemble early meadow-rue (T. dioicum) however the two can be separated based on the length of the petiole of the leaf that subtends the inflorescence. Thalictrum venulosum has a short petiole (up to 3 cm), whereas T. dioicum is longer (up to 6 cm).

Ecological characteristics: Historic locations for this plant have been along river banks in northern Maine.

Phenology: Flowering in June and July

Family: Ranunculaceae

Photo: Thalictrum venulosum

Synonyms: Maine populations are represented by the variety confine (Fern.) Boivin. Formerly referred to as Thalictrum confine Fern.

Known Distribution in Maine: This rare plant has historically been documented from a total of 3 towns in the following county: Aroostook

Dates of documented observations are: 1902, 1940, 1941

Reason(s) for rarity: At southern limit of range.

Conservation considerations: Unknown; has not been seen recently. Changes in hydrology along the rivers where a population once occurred may have been detrimental.